Could we capture and store energy from lightning?

In parts of Venezuela, there are lightning storms almost 300 nights each year, producing skies so bright that navigators once used them as a lighthouse. So could lightning be used to power the planet instead of fossil fuels? Karl Kruszelnicki finds out.

Well, to answer that, the obvious place to is a lightning capital of the world: Lake Maracaibo in the state of Zulia in Venezuela.

Before I did the numbers, my gut feeling wrongly told me that the energy from lightning could easily provide bulk energy for the whole world.

Venezuela is so far north in the continent of South America that it actually sits in the Northern Hemisphere, running from the Equator to about 10 degrees north.

In Lake Maracaibo, lightning storms happen about 297 days of each year. That's over 80 per cent of the time.

In fact, the locals have put a lightning bolt on the official state flag—to fit in better with the scenery.

Now Lake Maracaibo is not actually a lake, because it is connected to the sea by the Tablazo Strait. This strait is over five kilometres wide where it meets the Gulf of Venezuela.

This so-called 'lake' is about 200 kilometres across, and is a major shipping route for Venezuela's crude oil. But if the locals call it a lake, I'm happy to play along.

So far, we've got the lake—which is not really a lake—in a part of South America, which is actually in the Northern Hemisphere.

Lightning storms are so constant that they've earned the name 'the Never-Ending Storm of Catatumbo'. The name comes from the Catatumbo River that empties into Lake Maracaibo.

The water is warm, and the atmosphere is very humid—after all, it's only 10 degrees from the Equator. But the mouth of the river is surrounded on three sides, like a horseshoe, by three mountain ranges.

When the cold dry air from the mountains meets the hot and humid air, you've got the best possible conditions for lightning. The storm clouds build up to an altitude of over a kilometre.

Within an hour of the storm clouds forming, the lightning starts flashing. The flash rate quickly accelerates up to 200 flashes per second. A typical lightning storm lasts for 10 hours, and this happens nearly 300 nights each year.

The clouds are like an enormous light bulb, flashing in the sky. It's bright enough to read a newspaper in the middle of the night. The storms reach their peak in September, but according to the locals, the prettiest storms happen in November each year.

These storms are so powerful and so regular that they have been used by European navigators for the last four centuries as a natural lighthouse. In fact, they're nicknamed 'Maracaibo's Lighthouse'.

So we've come to the right place to develop the technology to capture and use lightning. But before we start thinking about lightning rods and enormous banks of tens of thousands of giant ultra-capacitors, let's take a look at what the scientists would call the numbers.

Typically, each lightning bolt carries about 500 megajoules (MJ) of energy. What does that mean in plain English?

First, 500 MJ is the amount of energy needed to run an average Western house for about a week. Second, 500 MJ is the amount of energy in about 38 litres of petrol or gasoline (or about 10 US gallons). And third, 500 MJ is enough energy to boil about 1,500 kettles of water.

Suppose that we could capture all the energy from all the 1.4 billion lightning bolts that happen each year. In that case, we would have enough energy to make 100 cups of tea for each human on the planet, each year. That works out to a cuppa every three or four days.

Now that's quite surprising. Before I did the numbers, my gut feeling wrongly told me that the energy from lightning could easily provide bulk energy for the whole world. Instead, all it would do is give you a few cups of tea each week.

Even though lightning is very impressive, it's no match for the energy-hungry society that we humans have developed over the last few centuries.

With no trouble at all, we can easily burn more than 38 litres of petrol in travelling from one Australian capital city to the next—and that's the amount of energy in just one lightning bolt.

So harnessing lightning can't compete with fossil fuels, but it's still enough for a cuppa, so enjoy that zap of energy while you can.

Editor's note: An earlier version of this article stated that 38 litres of petrol or 4.2 US gallons. In fact, 38 litres is 10 gallons.

Comments (14)

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Alan :

14 Feb 2017 11:54:38am

Disappointed. I wanted to know if there were any technologies capable of harvesting any of the static build up. Catching a 'bolt' seems a tad optimistic given the peak current/power present. Also, my house (electric hot water and cooking) runs at around 150kWh a week.

PM1957 :

BB :

14 Feb 2017 1:29:23pm

But is it feasible? That's the question.

Granted there's not a huge amount of energy to be derived globally but would it be worth it for a place that gets irregular lightning to bother building the infrastructure to harness lightning strikes. How much would such infrastructure cost?

John :

14 Feb 2017 8:29:46pm

I'd like to know if you think the energy can be harvested. Never mind that it won't produce all of the energy that the world needs. If it is feasible it would be a welcome addition to the other renewable energy sources being developed. What is an ultra-capacitor anyway and how would they work?

Tony :

15 Feb 2017 8:12:08am

Assuming 700 billion MJ of energy and a pop of 7 billion that would be 100MJ per person per year. That would boil 300 kettles and make between 1200 and 1500 cups of tea, depending on the size of the cup.

Chris :

15 Feb 2017 9:05:55am

Since I haven't had my first coffee, I probably can't do math, but I'll risk it- maybe it should be three or four cuppa's a day each? 1,500 kettles x 1.4 billion strikes / 7 billion people /365 days = 0.8 kettles each per day, and I recon I can get 4 cuppa's from a kettle. I'm sure you could run the world on that.

Alex Nelson :

15 Feb 2017 9:07:19am

This article is illuminating - please pardon the pun. A long time ago I wondered about the feasibility of tapping the energy from the lightning of the spectacular storms over the Top End of the Northern Territory. I envisaged a line or grid of towers, acting like lightning rods, connected to some kind of underground heat reservoir (containing molten salt, for example) from which energy could be derived as needed. It seems from this story I should just enjoy nature's electrical displays from safe vantage points - and dream on.

niloc :

Dr Andrew Allison :

15 Feb 2017 3:59:59pm

As an electrical engineer, I have carried out similar "back of the envelope" calculations to Dr Karl, and I have come to similar conclusions.

There are a few special practical difficulties with the idea of capturing lightning. The main problem is that lightning conveys an immense amount of power for a short period of time. Any collection devices would have to be very robust. Also, there is a problem with loss, or damage, in the storage device. Most storage devices are most efficient if you charge them up slowly, and discharge them slowly. It would be difficult to efficiently smooth out such an impulsive source as lightning.